For a Registrant, there's no "opt-out" for .COM domains in the same way that individuals who register a .UK domain can "opt-out".
The non-recommended way of preventing your private data from being displayed is to falsify it, although this breaches the terms and conditions that you'll have agreed to at the time you registered the domain.
The more common way of going about hiding your data is to make use of one of the numerous "private registration" services that are available. These services use legitimate third party details for the Registrant address and keep your registration within the guidelines. The down side is that you'll have to pay for such services, but you'll only be looking at maybe $10 to $15 per annum.
Set up a fictitious name company (in US it's a non-corporation, generally a sole proprietorship) and register any domains under it and that why you won’t violate any TOS and you would keep your private info private. In Pennsylvania I think a fictitious name filing is $75.00.
If I learned to type better, I wouldn't have to keep editing my posts :)
[edited by: Marshall at 1:27 pm (utc) on June 29, 2007]